Noninvasive cardiac therapy evaluation

ABSTRACT

Systems, methods, and interfaces are described herein for assisting a user in noninvasive evaluation of patients for cardiac therapy and noninvasive evaluation of cardiac therapy being delivered. The systems, methods, and interfaces may provide graphical representations of cardiac electrical activation times about one or more portions of human anatomy and one or more cardiac health metrics.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication 61/913,743 entitled “Noninvasive Cardiac Therapy Evaluation”and filed on Dec. 9, 2013, which is incorporated herein by reference inits entirety.

BACKGROUND

The disclosure herein relates to systems, methods, and interfaces foruse in the noninvasive evaluation of patients for cardiac therapy andnoninvasive evaluation of cardiac therapy being performed on patients.

Cardiac therapy, such as cardiac resynchronization therapy (CRT), maycorrect symptoms of electrical dyssynchrony of a patient's heart byproviding pacing therapy to one or both ventricles or atria, e.g., byproviding pacing to encourage earlier activation of the left or rightventricles. By pacing the contraction of the ventricles, the ventriclesmay be controlled so that the ventricles contract in synchrony. Somepatients undergoing cardiac therapy have experienced improved ejectionfraction, increased exercise capacity, and an improved feeling ofwell-being.

Providing cardiac therapy to a patient may involve determining whetherthe patient will derive benefit from the cardiac therapy prior toimplantation of a cardiac rhythm device, determining optimal site forplacement of one or more ventricular pacing leads, and programming ofdevice parameters, such as selection of electrodes on multi polar rightor left ventricular leads, as well as selection of the timing of thepacing pulses delivered to the electrodes, such as atrioventricular(A-V) and intra-ventricular (V-V) delays.

SUMMARY

The exemplary systems, methods, and interfaces described herein may beconfigured to assist a user (e.g., a physician) in evaluating a patientfor cardiac therapy and/or evaluating on-going cardiac therapy (e.g.,cardiac therapy being performed on a patient). The systems, methods, andinterfaces may be described as being noninvasive. For example, thesystems, methods, and interfaces may not use implantable devices such asleads, probes, catheters, etc. to evaluate a patient for cardiac therapyand/or to evaluate on-going cardiac therapy. Instead, the systems,methods, and interfaces may use electrical measurements takennoninvasively using, e.g., a plurality of external electrodes attachedto the skin of a patient about the patient's torso.

More specifically, the exemplary systems and methods may providegraphical user interfaces configured to assist a user in ascertaining,or assessing, whether a patient may benefit from cardiac therapy and/orwhether cardiac therapy being delivered to the patient is beneficial.The exemplary graphical user interfaces may be configured to displayelectrical activation times about one or more portions of human anatomy,one or more metrics of the patient's cardiac health, and an indicationof whether cardiac therapy may be beneficial for the patient and/orwhether the on-going cardiac therapy appears to be beneficial (e.g.,when compared to the patient's cardiac health prior to cardiac therapy,etc.).

An exemplary system for assisting in noninvasive evaluation of a patientfor cardiac therapy may include electrode apparatus, a displayapparatus, and computing apparatus coupled to the electrode apparatusand the display apparatus. The electrode apparatus may include aplurality of external electrodes configured to be located proximatetissue of a patient (e.g., surface electrodes positioned in an arrayconfigured to be located proximate the skin of the torso of thepatient). The display apparatus may include a graphical user interfaceconfigured to present cardiac electrical activation time information andcardiac health information. The computing apparatus may be configured toprovide the graphical user interface displayed on the display apparatusto assist a user in noninvasively evaluating the patient for cardiactherapy. The computing apparatus may be further configured to: measuresurrogate cardiac electrical activation times using one or more externalelectrodes of the plurality of external electrodes of the electrodeapparatus proximate the patient's heart, display, on the graphical userinterface, a graphical representation of the measured surrogate cardiacelectrical activation times about a portion of human anatomy (e.g.,color scaling the portion of human anatomy on the graphical userinterface according to the measured surrogate cardiac electricalactivation times), measure at least one metric of the patient's cardiachealth (e.g., QRS width, electrical dyssynchrony, etc.) using one ormore external electrodes of the plurality of external electrodes of theelectrode apparatus proximate the patient's heart, display, on thegraphical user interface, the at least one metric of the patient'scardiac health, and display, on the graphical user interface, anindication of whether cardiac therapy for the patient may be beneficial.

An exemplary computer-implemented method for assisting in noninvasiveevaluation of a patient for cardiac therapy may include measuringsurrogate cardiac electrical activation times using one or more externalelectrodes proximate the patient's heart (e.g., surface electrodespositioned in an array configured to be located proximate the skin ofthe torso of the patient), displaying a graphical user interface agraphical representation of the measured surrogate cardiac electricalactivation times about a portion of human anatomy (e.g., color scalingthe portion of human anatomy on the graphical user interface accordingto the measured surrogate cardiac electrical activation times),measuring at least one metric of the patient's cardiac health (e.g., QRSwidth, electrical dyssynchrony, etc.) using one or more externalelectrodes proximate the patient's heart, displaying, on the graphicaluser interface, the at least one metric of the patient's cardiac health,and displaying, on the graphical user interface, an indication ofwhether cardiac therapy for the patient may be beneficial.

Another exemplary system for assisting in noninvasive evaluation of apatient for cardiac therapy may include means for measuring surrogatecardiac electrical activation times representative of the electricalactivation times of a patient's heart, means for measuring at least onemetric of the patient's cardiac health (e.g., QRS width, electricaldyssynchrony, etc.), display means for displaying, on a graphical userinterface, a graphical representation of the measured surrogate cardiacelectrical activation times about a portion of human anatomy (e.g.,color scaling the portion of human anatomy on the graphical userinterface according to the measured surrogate cardiac electricalactivation times), the at least one metric of the patient's cardiachealth, and an indication of whether cardiac therapy for the patient maybe beneficial.

In one or more exemplary embodiments, displaying the graphicalrepresentation of the measured surrogate cardiac electrical activationtimes about a portion of human anatomy may include displaying agraphical representation of the measured surrogate cardiac electricalactivation times about a graphical representation of at least one of ananterior side of a human torso and a posterior side of a human torso.

In one or more exemplary embodiments, displaying the graphicalrepresentation of the measured surrogate cardiac electrical activationtimes about a portion of human anatomy may include displaying agraphical representation of the measured surrogate cardiac electricalactivation times about a graphical representation of at least one of ananterior side of a heart and a posterior side of a heart.

One or more exemplary embodiments may further include displaying, on thegraphical user interface, at least one electrocardiogram of the patient,wherein each of the at least one electrocardiogram are captured using atleast one different electrode, and wherein the at least oneelectrocardiogram is time-aligned on the graphical user interface and/orstoring the surrogate cardiac electrical activation times, the at leastone metric of the patient's cardiac health, and the at least oneelectrocardiogram for use in comparisons at a later time.

An exemplary system for assisting in noninvasive evaluation of cardiactherapy may include electrode apparatus, a display apparatus, andcomputing apparatus coupled to the electrode apparatus and the displayapparatus. The electrode apparatus may include a plurality of externalelectrodes configured to be located proximate tissue of a patient (e.g.,surface electrodes positioned in an array configured to be locatedproximate the skin of the torso of the patient). The display apparatusmay include a graphical user interface configured to present cardiacelectrical activation time information and cardiac health information.The computing apparatus may be configured to provide the graphical userinterface displayed on the display apparatus to assist a user innoninvasively evaluating cardiac therapy. The computing apparatus may befurther configured to measure surrogate cardiac electrical activationtimes using one or more external electrodes of the plurality of externalelectrodes of the electrode apparatus proximate the patient's heart,display, on the graphical user interface, a graphical representation ofpresently-measured surrogate cardiac electrical activation times about afirst human anatomy portion and a graphical representation ofpreviously-measured surrogate cardiac electrical activation times abouta second human anatomy portion (e.g., the first human anatomy portionand the second human anatomy portion may depict the same human anatomy),measure at least one metric of the patient's cardiac health (e.g., QRSwidth, electrical dyssynchrony, etc.) using one or more externalelectrodes of the plurality of external electrodes of the electrodeapparatus proximate the patient's heart, display, on the graphical userinterface, at least one presently-measured metric of the patient'scardiac health and at least one previously-measured metric of thepatient's cardiac health, and display, on the graphical user interface,an indication of whether cardiac therapy for the patient appears to bebeneficial (e.g., a percentage improvement between the at least onepreviously-measured metric of the patient's cardiac health and the atleast one presently-measured metric of the patient's cardiac health).

One exemplary method for assisting in noninvasive evaluation of cardiactherapy may include measuring surrogate cardiac electrical activationtimes using one or more external electrodes proximate the patient'sheart and displaying a graphical user interface. The graphical userinterface may include a graphical representation of presently-measuredsurrogate cardiac electrical activation times about a first humananatomy portion, and a graphical representation of previously-measuredsurrogate cardiac electrical activation times about a second humananatomy portion (e.g., the first human anatomy portion and the secondhuman anatomy portion may depict the same human anatomy). The exemplarymethod may further include measuring at least one metric of thepatient's cardiac health (e.g., QRS width, electrical dyssynchrony,etc.) using one or more external electrodes proximate the patient'sheart and displaying, on the graphical user interface, at least onepresently-measured metric of the patient's cardiac health and at leastone previously-measured metric of the patient's cardiac health, anddisplaying, on the graphical user interface, an indication of whethercardiac therapy for the patient appears to be beneficial (e.g., apercentage improvement between the at least one previously-measuredmetric of the patient's cardiac health and the at least onepresently-measured metric of the patient's cardiac health).

One exemplary system for assisting in noninvasive evaluation of apatient for cardiac therapy may include means for measuring surrogatecardiac electrical activation times representative of the electricalactivation times of a patient's heart, means for measuring at least onemetric of the patient's cardiac health (e.g., QRS width, electricaldyssynchrony, etc.), and display means for displaying, on a graphicaluser interface, a graphical representation of presently-measuredsurrogate cardiac electrical activation times about a first humananatomy portion and a graphical representation of previously-measuredsurrogate cardiac electrical activation times about a second humananatomy portion (e.g., the first human anatomy portion and the secondhuman anatomy portion may depict the same human anatomy), at least onepresently-measured metric of the patient's cardiac health and at leastone previously-measured metric of the patient's cardiac health, and anindication of whether cardiac therapy for the patient appears to bebeneficial (e.g., a percentage improvement between the at least onepreviously-measured metric of the patient's cardiac health and the atleast one presently-measured metric of the patient's cardiac health).

One or more exemplary embodiments may further include allowing the userto change at least one pacing parameter of an implantable medical deviceproviding cardiac therapy to the patient (e.g., at least one of a pacingtiming interval, a pacing vector, and a pacing mode) and/or displaying,on the graphical user interface, mechanical motion information of one ormore regions of at least a portion of blood vessel anatomy of thepatient's heart.

In one or more exemplary embodiments, displaying graphicalrepresentations of the measured surrogate cardiac electrical activationtimes about the first and second human anatomy portions may includedisplaying graphical representations of the measured surrogate cardiacelectrical activation times about graphical representations of at leastone of an anterior side of a human torso and a posterior side of a humantorso.

In one or more exemplary embodiments, displaying graphicalrepresentations of the measured surrogate cardiac electrical activationtimes about the first and second human anatomy portions may includedisplaying graphical representations of the measured surrogate cardiacelectrical activation times about graphical representations of at leastone of an anterior side of a heart and a posterior side of a heart.

In one or more exemplary embodiments, displaying the graphicalrepresentations of the measured surrogate cardiac electrical activationtimes about a portion of human anatomy may include color scaling theportions of human anatomy on the graphical user interface according tothe measured surrogate cardiac electrical activation times.

One or more exemplary embodiments may further include displaying, on agraphical user interface, at least one electrocardiogram of the patient.Each of the at least one electrocardiogram may be captured using atleast one different electrode and may be time-aligned on the graphicaluser interface.

One exemplary system for assisting in noninvasive evaluation of cardiactherapy may include electrode apparatus (e.g., including a plurality ofexternal electrodes configured to be located proximate tissue of apatient), a display apparatus (e.g., including a graphical userinterface configured to present cardiac electrical activation timeinformation and cardiac health information), and computing apparatuscoupled to the electrode apparatus and the display apparatus. Thecomputing apparatus may be configured to provide the graphical userinterface displayed on the display apparatus. The computing apparatusmay be further configured to measure surrogate cardiac electricalactivation times using one or more external electrodes of the pluralityof external electrodes of the electrode apparatus proximate thepatient's heart, measure at least one metric of the patient's cardiachealth using one or more external electrodes of the plurality ofexternal electrodes of the electrode apparatus proximate the patient'sheart, and allow a user to select one of initial examination mode forassisting a user in noninvasively evaluating the patient for cardiactherapy and follow-up examination mode for assisting a user innoninvasively evaluating cardiac therapy after implantation cardiactherapy. When in initial examination mode, the computing apparatus maybe configured to display, on the graphical user interface, a graphicalrepresentation of the measured surrogate cardiac electrical activationtimes about a portion of human anatomy, at least one metric of thepatient's cardiac health, and an indication of whether cardiac therapyfor the patient may be beneficial. When in follow-up examination mode,the computing apparatus may be configured to display, display, on thegraphical user interface, a graphical representation ofpresently-measured surrogate cardiac electrical activation times about afirst human anatomy portion and a graphical representation ofpreviously-measured surrogate cardiac electrical activation times abouta second human anatomy portion and at least one presently-measuredmetric of the patient's cardiac health, at least one previously-measuredmetric of the patient's cardiac health, and an indication of whethercardiac therapy for the patient appears to be beneficial.

One exemplary a computer-implemented method for assisting in noninvasiveevaluation of a patient for cardiac therapy may include measuringsurrogate cardiac electrical activation times using one or more externalelectrodes proximate the patient's heart, measuring at least one metricof the patient's cardiac health using one or more external electrodesproximate the patient's heart, and allowing a user to select one ofinitial examination mode and follow-up examination mode. The initialexamination mode may be configured for assisting a user in noninvasivelyevaluating the patient for cardiac therapy and the follow-up examinationmode may be configured for assisting a user in noninvasively evaluatingcardiac therapy after implantation cardiac therapy. When in initialexamination mode, the exemplary method display, on a graphical userinterface, a graphical representation of the measured surrogate cardiacelectrical activation times about a portion of human anatomy, at leastone metric of the patient's cardiac health, and an indication of whethercardiac therapy for the patient may be beneficial. When in follow-upexamination mode, the exemplary method display, on a graphical userinterface, a graphical representation of presently-measured surrogatecardiac electrical activation times about a first human anatomy portionand a graphical representation of previously-measured surrogate cardiacelectrical activation times about a second human anatomy portion and atleast one presently-measured metric of the patient's cardiac health, atleast one previously-measured metric of the patient's cardiac health,and an indication of whether cardiac therapy for the patient appears tobe beneficial.

Another exemplary system for assisting in noninvasive evaluation of apatient for cardiac therapy may include means for measuring surrogatecardiac electrical activation times representative of the electricalactivation times of a patient's heart, means for measuring at least onemetric of the patient's cardiac health, and computing means for allowinga user to select one of initial examination mode and follow-upexamination mode. The initial examination mode may be configured forassisting a user in noninvasively evaluating the patient for cardiactherapy and the follow-up examination mode may be configured forassisting a user in noninvasively evaluating cardiac therapy afterimplantation cardiac therapy. The exemplary system may further includedisplay means for, when in initial examination mode, displaying, on agraphical user interface, a graphical representation of the measuredsurrogate cardiac electrical activation times about a portion of humananatomy, at least one metric of the patient's cardiac health, and anindication of whether cardiac therapy for the patient may be beneficial,and when in follow-up examination mode, displaying, on a graphical userinterface, a graphical representation of presently-measured surrogatecardiac electrical activation times about a first human anatomy portionand a graphical representation of previously-measured surrogate cardiacelectrical activation times about a second human anatomy portion and atleast one presently-measured metric of the patient's cardiac health, atleast one previously-measured metric of the patient's cardiac health,and an indication of whether cardiac therapy for the patient appears tobe beneficial.

In one or more exemplary embodiments, a user may be allowed to select animplantation examination mode for assisting a user in noninvasivelyevaluating cardiac therapy during implantation and configuration of acardiac therapy. When in implantation examination mode, a graphicalrepresentation of presently-measured surrogate cardiac electricalactivation times about a first human anatomy portion and a graphicalrepresentation of previously-measured surrogate cardiac electricalactivation times about a second human anatomy portion and at least onepresently-measured metric of the patient's cardiac health, at least onepreviously-measured metric of the patient's cardiac health, and anindication of whether cardiac therapy for the patient appears to bebeneficial may be displayed on a graphical user interface. In at leastone embodiment, a user may be allowed to change at least one pacingparameter of an implantable medical device providing cardiac therapy tothe patient.

The above summary is not intended to describe each embodiment or everyimplementation of the present disclosure. A more complete understandingwill become apparent and appreciated by referring to the followingdetailed description and claims taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram of an exemplary system including electrodeapparatus, display apparatus, and computing apparatus.

FIGS. 2A-2B are diagrams of exemplary external electrode apparatus formeasuring torso-surface potentials.

FIG. 3 is a block diagram of exemplary modes for noninvasive cardiacevaluation.

FIG. 4 is an exemplary initial examination graphical user interfacedepicting electrical activation information, cardiac health metrics, andan indication of the benefit of cardiac therapy.

FIG. 5 is a graphical representation of a human heart includingactivation times mapped thereon.

FIG. 6 is an exemplary implant examination graphical user interfacedepicting previously- and presently-measured electrical activationinformation and cardiac health metrics.

FIG. 7 is a block diagram of an exemplary method of noninvasiveevaluation of cardiac therapy for a patient and configuration cardiactherapy.

FIG. 8 is an exemplary follow-up examination graphical user interfacedepicting previously- and presently-measured electrical activationinformation and cardiac health metrics.

FIG. 9 is a diagram of an exemplary system including an exemplaryimplantable medical device (IMD).

FIG. 10A is a diagram of the exemplary IMD of FIG. 9.

FIG. 10B is a diagram of an enlarged view of a distal end of theelectrical lead disposed in the left ventricle of FIG. 10A.

FIG. 11A is a block diagram of an exemplary IMD, e.g., the IMD of FIGS.9-10.

FIG. 11B is another block diagram of an exemplary IMD (e.g., animplantable pulse generator) circuitry and associated leads employed inthe system of FIGS. 9-10 for providing three sensing channels andcorresponding pacing channels.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

In the following detailed description of illustrative embodiments,reference is made to the accompanying figures of the drawing which forma part hereof, and in which are shown, by way of illustration, specificembodiments which may be practiced. It is to be understood that otherembodiments may be utilized and structural changes may be made withoutdeparting from (e.g., still falling within) the scope of the disclosurepresented hereby.

Exemplary systems, apparatus, and methods shall be described withreference to FIGS. 1-11. It will be apparent to one skilled in the artthat elements or processes from one embodiment may be used incombination with elements or processes of the other embodiments, andthat the possible embodiments of such methods, apparatus, and systemsusing combinations of features set forth herein is not limited to thespecific embodiments shown in the Figures and/or described herein.Further, it will be recognized that the embodiments described herein mayinclude many elements that are not necessarily shown to scale. Stillfurther, it will be recognized that timing of the processes and the sizeand shape of various elements herein may be modified but still fallwithin the scope of the present disclosure, although certain timings,one or more shapes and/or sizes, or types of elements, may beadvantageous over others.

From unipolar electrocardiogram (ECG) recordings, cardiac electricalactivation times can be detected or estimated in proximity of areference location (e.g., which can be a chosen location for the leftventricle lead during implant). Such electrical activation times may bemeasured and displayed, or conveyed, to an implanter by a system whichacquires the ECG signals and generates the metric of electricalactivation times (e.g., depolarization) measured from various ECGlocations. As described herein, at least in one or more embodiments,electrical activation times displayed on a graphical user interface maybe used in noninvasive evaluation of a patient for cardiac therapyand/or evaluation of cardiac therapy.

Various exemplary systems, methods, and interfaces may be configured touse electrode apparatus including external electrodes, displayapparatus, and computing apparatus to noninvasively assist a user (e.g.,a physician) in the evaluation of a patient for cardiac therapy and/orevaluation of cardiac therapy. An exemplary system 100 includingelectrode apparatus 110, display apparatus 130, and computing apparatus140 is depicted in FIG. 1.

The electrode apparatus 110 as shown includes a plurality of electrodesincorporated, or included within a band wrapped around the chest, ortorso, of a patient 14. The electrode apparatus 110 is operativelycoupled to the computing apparatus 140 (e.g., through one or wiredelectrical connections, wirelessly, etc.) to provide electrical signalsfrom each of the electrodes to the computing apparatus 140 for analysis.Exemplary electrode apparatus may be described in U.S. ProvisionalPatent Application 61/913,759 entitled “Bioelectric Sensor Device andMethods” and filed on Dec. 9, 2013 and U.S. patent application entitled“Bioelectric Sensor Device and Methods” and filed on even date herewith(Docket No. C00006744.USU2 (134.0793 0101)), each of which isincorporated herein by reference in its entirety. Further, exemplaryelectrode apparatus 110 will be described in more detail in reference toFIGS. 2A-2B.

Although not described herein, the exemplary system 100 may furtherinclude imaging apparatus. The imaging apparatus may be any type ofimaging apparatus configured to image, or provide images of, at least aportion of the patient in a noninvasive manner. For example, the imagingapparatus may not use any components or parts that may be located withinthe patient to provide images of at least a portion of the patientexcept noninvasive tools such as contrast solution. It is to beunderstood that the exemplary systems, methods, and interfaces describedherein may noninvasively assist a user (e.g., a physician) in evaluationof a patient for cardiac therapy and/or on-going cardiac therapydelivered to a patient, and after the exemplary systems, methods, andinterfaces have provided the noninvasive assistance, the exemplarysystems, methods, and interfaces may then provide assistance to implant,or navigate, an implantable electrode into the patient, e.g., proximatethe patient's heart, using imaging apparatus.

For example, after the exemplary systems, methods, and interfaces haveprovided noninvasive assistance, the exemplary systems, methods, andinterfaces may then provide image guided navigation that may be used tonavigate leads including electrodes, leadless electrodes, wirelesselectrodes, catheters, etc., within the patient's body. Further,although the exemplary systems, methods, and interfaces are describedherein with reference to a patient's heart, it is to be understood thatthe exemplary systems, methods, and interfaces may be applicable to anyother portion of the patient's body. Exemplary systems and methods thatuse imaging apparatus and/or electrode apparatus may be described inU.S. patent application Ser. No. 13/916,353 filed on Jun. 12, 2013 andentitled “Implantable Electrode Location Selection,” U.S. patentapplication Ser. No. 13/916,377 filed on Jun. 12, 2013 and entitled“Implantable Electrode Location Selection,” U.S. Provisional PatentApplication No. 61/817,483 filed on Apr. 30, 2013 and entitled“Identifying Effective Electrodes,” U.S. Provisional Patent Application61/817,480 filed on Apr. 30, 2013 and entitled “Identifying OpticalElectrical Vectors,” U.S. Provisional Patent Application 61/913,795entitled “Systems, Methods, and Interfaces for Identifying EffectiveElectrodes” and filed on Dec. 9, 2013, U.S. patent application entitled“Systems, Methods, and Interfaces for Identifying Effective Electrodes”(Medtronic Docket No. C00002332.USU3/MRG 134.0737 0101) and filed oneven date herewith, U.S. Provisional Patent Application 61/913,784entitled “Systems, Methods, and Interfaces for Identifying OptimalElectrical Vectors” and filed on Dec. 9, 2013, and U.S. patentapplication entitled “Systems, Methods, and Interfaces for IdentifyingOptimal Electrical Vectors” (Medtronic Docket No. C00005189.USU3/MRG134.0736 0101) and filed on even date herewith, each of which isincorporated herein by reference in its entirety.

Exemplary imaging apparatus may be configured to capture x-ray imagesand/or any other alternative imaging modality. For example, the imagingapparatus may be configured to capture images, or image data, usingisocentric fluoroscopy, bi-plane fluoroscopy, ultrasound, computedtomography (CT), multi-slice computed tomography (MSCT), magneticresonance imaging (MRI), high frequency ultrasound (HIFU), opticalcoherence tomography (OCT), intra-vascular ultrasound (IVUS), twodimensional (2D) ultrasound, three dimensional (3D) ultrasound, fourdimensional (4D) ultrasound, intraoperative CT, intraoperative MRI, etc.Further, it is to be understood that the imaging apparatus may beconfigured to capture a plurality of consecutive images (e.g.,continuously) to provide video frame data. In other words, a pluralityof images taken over time using the imaging apparatus may provide motionpicture data. Additionally, the images may also be obtained anddisplayed in two, three, or four dimensions. In more advanced forms,four-dimensional surface rendering of the heart or other regions of thebody may also be achieved by incorporating heart data or other softtissue data from an atlas map or from pre-operative image data capturedby MRI, CT, or echocardiography modalities. Image datasets from hybridmodalities, such as positron emission tomography (PET) combined with CT,or single photon emission computer tomography (SPECT) combined with CT,could also provide functional image data superimposed onto anatomicaldata to be used to confidently reach target locations within the heartor other areas of interest.

Examples of systems and/or imaging apparatus may be described in U.S.Pat. App. Pub. No. 2005/0008210 to Evron et al. published on Jan. 13,2005, U.S. Pat. App. Pub. No. 2006/0074285 to Zarkh et al. published onApr. 6, 2006, U.S. Pat. App. Pub. No. 2011/0112398 to Zarkh et al.published on May 12, 2011, U.S. Pat. App. Pub. No. 2013/0116739 to Bradaet al. published on May 9, 2013, U.S. Pat. No. 6,980,675 to Evron et al.issued on Dec. 27, 2005, U.S. Pat. No. 7,286,866 to Okerlund et al.issued on Oct. 23, 2007, U.S. Pat. No. 7,308,297 to Reddy et al. issuedon Dec. 11, 2011, U.S. Pat. No. 7,308,299 to Burrell et al. issued onDec. 11, 2011, U.S. Pat. No. 7,321,677 to Evron et al. issued on Jan.22, 2008, U.S. Pat. No. 7,346,381 to Okerlund et al. issued on Mar. 18,2008, U.S. Pat. No. 7,454,248 to Burrell et al. issued on Nov. 18, 2008,U.S. Pat. No. 7,499,743 to Vass et al. issued on Mar. 3, 2009, U.S. Pat.No. 7,565,190 to Okerlund et al. issued on Jul. 21, 2009, U.S. Pat. No.7,587,074 to Zarkh et al. issued on Sep. 8, 2009, U.S. Pat. No.7,599,730 to Hunter et al. issued on Oct. 6, 2009, U.S. Pat. No.7,613,500 to Vass et al. issued on Nov. 3, 2009, U.S. Pat. No. 7,742,629to Zarkh et al. issued on Jun. 22, 2010, U.S. Pat. No. 7,747,047 toOkerlund et al. issued on Jun. 29, 2010, U.S. Pat. No. 7,778,685 toEvron et al. issued on Aug. 17, 2010, U.S. Pat. No. 7,778,686 to Vass etal. issued on Aug. 17, 2010, U.S. Pat. No. 7,813,785 to Okerlund et al.issued on Oct. 12, 2010, U.S. Pat. No. 7,996,063 to Vass et al. issuedon Aug. 9, 2011, U.S. Pat. No. 8,060,185 to Hunter et al. issued on Nov.15, 2011, and U.S. Pat. No. 8,401,616 to Verard et al. issued on Mar.19, 2013, each of which are incorporated herein by reference in theirentireties.

The display apparatus 130 and the computing apparatus 140 may beconfigured to display and analyze data such as, e.g., surrogateelectrical activation information or data, electrocardiogram data, etc.gathered, or collected, using the electrode apparatus 110. In at leastone embodiment, the computing apparatus 140 may be a server, a personalcomputer, or a tablet computer. The computing apparatus 140 may beconfigured to receive input from input apparatus 142 and transmit outputto the display apparatus 130. Further, the computing apparatus 140 mayinclude data storage that may allow for access to processing programs orroutines and/or one or more other types of data, e.g., for driving agraphical user interface configured to noninvasively assist a user inlocation selection of an implantable electrode, etc.

The computing apparatus 140 may be operatively coupled to the inputapparatus 142 and the display apparatus 130 to, e.g., transmit data toand from each of the input apparatus 142 and the display apparatus 130.For example, the computing apparatus 140 may be electrically coupled toeach of the input apparatus 142 and the display apparatus 130 using,e.g., analog electrical connections, digital electrical connections,wireless connections, bus-based connections, network-based connections,internet-based connections, etc. As described further herein, a user mayprovide input to the input apparatus 142 to manipulate, or modify, oneor more graphical depictions displayed on the display apparatus 130 toview and/or select one or more pieces of information related to apatient's cardiac health as further described herein.

Although as depicted the input apparatus 142 is a keyboard, it is to beunderstood that the input apparatus 142 may include any apparatuscapable of providing input to the computing apparatus 140 to perform thefunctionality, methods, and/or logic described herein. For example, theinput apparatus 142 may include a mouse, a trackball, a touchscreen(e.g., capacitive touchscreen, a resistive touchscreen, a multi-touchtouchscreen, etc.), etc. Likewise, the display apparatus 130 may includeany apparatus capable of displaying information to a user, such as agraphical user interface 132 including graphical depictions of anatomyof a human heart, images or graphical depictions of the patient's heart,graphical depictions of locations of one or more electrodes, graphicaldepictions of a human torso, images or graphical depictions of thepatient's torso, alphanumeric representations of one or more values,graphical depictions or actual images of implanted electrodes and/orleads, etc. For example, the display apparatus 130 may include a liquidcrystal display, an organic light-emitting diode screen, a touchscreen,a cathode ray tube display, etc.

The graphical user interfaces 132 displayed by the display apparatus 130may include, or display, one or more regions used to display graphicaldepictions, to display images, to allow selection of one or more regionsor areas of such graphical depictions and images, etc. As used herein, a“region” of a graphical user interface 132 may be defined as a portionof the graphical user interface 132 within which information may bedisplayed or functionality may be performed. Regions may exist withinother regions, which may be displayed separately or simultaneously. Forexample, smaller regions may be located within larger regions, regionsmay be located side-by-side, etc. Additionally, as used herein, an“area” of a graphical user interface 132 may be defined as a portion ofthe graphical user interface 132 located with a region that is smallerthan the region it is located within.

The processing programs or routines stored and/or executed by thecomputing apparatus 140 may include programs or routines forcomputational mathematics, matrix mathematics, decomposition algorithms,compression algorithms (e.g., data compression algorithms), calibrationalgorithms, image construction algorithms, signal processing algorithms(e.g., various filtering algorithms, Fourier transforms, fast Fouriertransforms, etc.), standardization algorithms, comparison algorithms,vector mathematics, or any other processing required to implement one ormore exemplary methods and/or processes described herein. Data storedand/or used by the computing apparatus 140 may include, for example,electrical signal/waveform data from the electrode apparatus 110,electrical activation times from the electrode apparatus 110, graphics(e.g., graphical elements, icons, buttons, windows, dialogs, pull-downmenus, graphic areas, graphic regions, 3D graphics, etc.), graphicaluser interfaces, results from one or more processing programs orroutines employed according to the disclosure herein, or any other datathat may be necessary for carrying out the one and/or more processes ormethods described herein.

In one or more embodiments, the exemplary systems, methods, andinterfaces may be implemented using one or more computer programsexecuted on programmable computers, such as computers that include, forexample, processing capabilities, data storage (e.g., volatile ornon-volatile memory and/or storage elements), input devices, and outputdevices. Program code and/or logic described herein may be applied toinput data to perform functionality described herein and generatedesired output information. The output information may be applied asinput to one or more other devices and/or methods as described herein oras would be applied in a known fashion.

The one or more programs used to implement the systems, methods, and/orinterfaces described herein may be provided using any programmablelanguage, e.g., a high level procedural and/or object orientatedprogramming language that is suitable for communicating with a computersystem. Any such programs may, for example, be stored on any suitabledevice, e.g., a storage media, that is readable by a general or specialpurpose program running on a computer system (e.g., including processingapparatus) for configuring and operating the computer system when thesuitable device is read for performing the procedures described herein.In other words, at least in one embodiment, the exemplary systems,methods, and/or interfaces may be implemented using a computer readablestorage medium, configured with a computer program, where the storagemedium so configured causes the computer to operate in a specific andpredefined manner to perform functions described herein. Further, in atleast one embodiment, the exemplary systems, methods, and/or interfacesmay be described as being implemented by logic (e.g., object code)encoded in one or more non-transitory media that includes code forexecution and, when executed by a processor, is operable to performoperations such as the methods, processes, and/or functionalitydescribed herein.

The computing apparatus 140 may be, for example, any fixed or mobilecomputer system (e.g., a controller, a microcontroller, a personalcomputer, mini computer, tablet computer, etc.). The exact configurationof the computing apparatus 130 is not limiting, and essentially anydevice capable of providing suitable computing capabilities and controlcapabilities (e.g., graphics processing, etc.) may be used. As describedherein, a digital file may be any medium (e.g., volatile or non-volatilememory, a CD-ROM, a punch card, magnetic recordable tape, etc.)containing digital bits (e.g., encoded in binary, trinary, etc.) thatmay be readable and/or writeable by computing apparatus 140 describedherein. Also, as described herein, a file in user-readable format may beany representation of data (e.g., ASCII text, binary numbers,hexadecimal numbers, decimal numbers, graphically, etc.) presentable onany medium (e.g., paper, a display, etc.) readable and/or understandableby a user.

In view of the above, it will be readily apparent that the functionalityas described in one or more embodiments according to the presentdisclosure may be implemented in any manner as would be known to oneskilled in the art. As such, the computer language, the computer system,or any other software/hardware which is to be used to implement theprocesses described herein shall not be limiting on the scope of thesystems, processes or programs (e.g., the functionality provided by suchsystems, processes or programs) described herein.

The electrical activation times of the patient's heart may be useful toevaluate a patient's cardiac health and/or to evaluate cardiac therapybeing delivered to a patient. Electrical activation information or dataof one or more regions of a patient's heart may be determined usingelectrode apparatus 110 as shown in FIG. 1 and in FIGS. 2A-2B. Theexemplary electrode apparatus 110 may be configured to measurebody-surface potentials of a patient 14 and, more particularly,torso-surface potentials of a patient 14. As shown in FIG. 2A, theexemplary electrode apparatus 110 may include a set, or array, ofelectrodes 112, a strap 113, and interface/amplifier circuitry 116. Theelectrodes 112 may be attached, or coupled, to the strap 113 and thestrap 113 may be configured to be wrapped around the torso of a patient14 such that the electrodes 112 surround the patient's heart. As furtherillustrated, the electrodes 112 may be positioned around thecircumference of a patient 14, including the posterior, lateral,posterolateral, and anterior locations of the torso of a patient 14.

Further, the electrodes 112 may be electrically connected tointerface/amplifier circuitry 116 via wired connection 118. Theinterface/amplifier circuitry 116 may be configured to amplify thesignals from the electrodes 112 and provide the signals to the computingapparatus 140. Other exemplary systems may use a wireless connection totransmit the signals sensed by electrodes 112 to the interface/amplifiercircuitry 116 and, in turn, the computing apparatus 140, e.g., aschannels of data. For example, the interface/amplifier circuitry 116 maybe electrically coupled to each of the computing apparatus 140 and thedisplay apparatus 130 using, e.g., analog electrical connections,digital electrical connections, wireless connections, bus-basedconnections, network-based connections, internet-based connections, etc.

Although in the example of FIG. 2A the electrode apparatus 110 includesa strap 113, in other examples any of a variety of mechanisms, e.g.,tape or adhesives, may be employed to aid in the spacing and placementof electrodes 112. In some examples, the strap 113 may include anelastic band, strip of tape, or cloth. In other examples, the electrodes112 may be placed individually on the torso of a patient 14. Further, inother examples, electrodes 112 (e.g., arranged in an array) may be partof, or located within, patches, vests, and/or other manners of securingthe electrodes 112 to the torso of the patient 14. Still further, inother examples, the electrodes 112 may be part of, or located within,two sections of material or two “patches.” One of the two sections orpatches may be located on the anterior side of the torso of the patient14 (to, e.g., measure surrogate cardiac electrical activation timesrepresentative of the anterior side of the patient's heart) and theother section or patch may be located on the posterior side of the torsoof the patient 14 (to, e.g., measure surrogate cardiac electricalactivation times representative of the posterior side of the patient'sheart).

The electrodes 112 may be configured to surround the heart of thepatient 14 and record, or monitor, the electrical signals associatedwith the depolarization and repolarization of the heart after thesignals have propagated through the torso of a patient 14. Each of theelectrodes 112 may be used in a unipolar configuration to sense thetorso-surface potentials that reflect the cardiac signals. Theinterface/amplifier circuitry 116 may also be coupled to a return orindifferent electrode (not shown) that may be used in combination witheach electrode 112 for unipolar sensing. In some examples, there may beabout 12 to about 50 electrodes 112 spatially distributed around thetorso of patient. Other configurations may have more or fewer electrodes112.

The computing apparatus 140 may record and analyze the torso-surfacepotential signals sensed by electrodes 112 and amplified/conditioned bythe interface/amplifier circuitry 116. The computing apparatus 140 maybe configured to analyze the signals from the electrodes 112 to providesurrogate electrical activation information or data such as surrogatecardiac electrical activation times, e.g., representative of actual, orlocal, electrical activation times of one or more regions of thepatient's heart as will be further described herein. For example,electrical signals measured at the left anterior surface location of apatient's torso may be representative, or surrogates, of electricalsignals of the left anterior left ventricle region of the patient'sheart, electrical signals measured at the left lateral surface locationof a patient's torso may be representative, or surrogates, of electricalsignals of the left lateral left ventricle region of the patient'sheart, electrical signals measured at the left posterolateral surfacelocation of a patient's torso may be representative, or surrogates, ofelectrical signals of the posterolateral left ventricle region of thepatient's heart, and electrical signals measured at the posteriorsurface location of a patient's torso may be representative, orsurrogates, of electrical signals of the posterior left ventricle regionof the patient's heart. In one or more embodiments, measurement ofactivation times can be performed by measuring time between the onset ofcardiac depolarization (e.g., onset of QRS complex) to the next theonset of cardiac depolarization. In one or more embodiments, measurementof activation times can be performed by picking an appropriate fiducialpoint (e.g., peak values, minimum values, minimum slopes, maximumslopes, zero crossings, threshold crossings, etc. of a near or far-fieldEGM) and measuring time between fiducial points (e.g., within theelectrical activity).

Additionally, the computing apparatus 140 may be configured to providegraphical user interfaces depicting the surrogate electrical activationtimes obtained using the electrode apparatus 110. Exemplary systems,methods, and/or interfaces may noninvasively use the electricalinformation collected using the electrode apparatus 110 to evaluate apatient for cardiac therapy and/or evaluate cardiac therapy beingdelivered to the patient.

FIG. 2B illustrates another exemplary electrode apparatus 110 thatincludes a plurality of electrodes 112 configured to surround the heartof the patient 14 and record, or monitor, the electrical signalsassociated with the depolarization and repolarization of the heart afterthe signals have propagated through the torso of the patient 14. Theelectrode apparatus 110 may include a vest 114 upon which the pluralityof electrodes 112 may be attached, or to which the electrodes 112 may becoupled. In at least one embodiment, the plurality, or array, ofelectrodes 112 may be used to collect electrical information such as,e.g., surrogate electrical activation times. Similar to the electrodeapparatus 110 of FIG. 2A, the electrode apparatus 110 of FIG. 2B mayinclude interface/amplifier circuitry 116 electrically coupled to eachof the electrodes 112 through a wired connection 118 and be configuredto transmit signals from the electrodes 112 to computing apparatus 140.As illustrated, the electrodes 112 may be distributed over the torso ofa patient 14, including, for example, the anterior, lateral, andposterior surfaces of the torso of the patient 14.

The vest 114 may be formed of fabric with the electrodes 112 attached tothe fabric. The vest 114 may be configured to maintain the position andspacing of electrodes 112 on the torso of the patient 14. Further, thevest 114 may be marked to assist in determining the location of theelectrodes 112 on the surface of the torso of the patient 14. In someexamples, there may be about 25 to about 256 electrodes 112 distributedaround the torso of the patient 14, though other configurations may havemore or fewer electrodes 112.

As described herein, the electrode apparatus 110 may be configured tomeasure electrical information (e.g., electrical signals) representingdifferent regions of a patient's heart. More specifically, activationtimes of different regions of a patient's heart can be approximated fromsurface electrocardiogram (ECG) activation times measured using surfaceelectrodes in proximity to surface areas corresponding to the differentregions of the patient's heart.

The exemplary systems, methods, and interfaces may be used in one ormore different settings to provide noninvasive assistance to a user inthe evaluation of a patient for cardiac therapy and/or evaluation ofon-going cardiac therapy (e.g., cardiac therapy beingpresently-delivered to a patient). Further, the exemplary systems,methods, and interfaces may be used to assist a user in theconfiguration and/or adjustment of one or more cardiac therapy settingsfor the cardiac therapy to be delivered to a patient or beingpresently-delivered to a patient.

To provide this functionality, the exemplary systems, methods, andinterfaces may be described as being configurable in a plurality ofmodes of operation 150 as depicted in FIG. 3. For example, the exemplarysystems, methods, and interfaces may be configured in an initialexamination mode 152, an implantation examination mode 154, and afollow-up examination mode 156.

The initial examination mode 152 may be configured for the noninvasiveevaluation of a patient for cardiac therapy. For example, the initialexamination mode 152 may be designed for an initialconsultation/evaluation of a patient considering cardiac therapy andwill be described further herein in reference to the exemplary initialexamination graphical user interface of FIG. 4.

The implantation examination mode 154 may be configured for thenoninvasive evaluation of cardiac therapy being delivered to a patientand/or being currently configured for a patient (e.g., duringconfiguration of cardiac resynchronization therapy (CRT) afterimplantation of the CRT device). For example, the implantationexamination mode 154 may be designed for use by a physician inevaluating cardiac therapy during implantation of a cardiac therapydevice, immediately after implantation of a cardiac therapy deviceand/or during configuration of the cardiac therapy immediately followingimplantation. Further, exemplary systems configurable in theimplantation examination mode 154 may include additional functionalitysuch as imaging and navigation functionality for electrode and/or leadplacement as described herein. The implantation examination mode 154will be described further herein in reference to the exemplaryimplantation examination graphical user interface of FIG. 6.

The follow-up examination mode 156 may be configured for the noninvasiveevaluation of cardiac therapy being delivered to a patient after acardiac therapy device has been delivering cardiac therapy to a patientfor a period of time (e.g., after implantation, not immediatelyfollowing implantation or initial configuration of the cardiac therapy,etc.). For example, the follow-up examination mode 156 may be designedfor use by a physician in evaluating cardiac therapy in follow-upappointments days, weeks, months, or years after a cardiac therapy hasbeen implanted in a patient and will be described further herein inreference to the exemplary follow-up examination graphical userinterface of FIG. 8.

The exemplary systems, methods, and interfaces may provide, or beconfigurable in, one or more of the plurality of modes 150. For example,an exemplary system may provide, or be configurable in, all of theplurality of modes 150. Further, for example, an exemplary system mayprovide, or be configurable in, two of the three modes 150 such as,e.g., the initial examination mode 152 and the follow-up mode 156. In atleast one embodiment, a system designed for use in an operating room ofa medical care facility (e.g., for the surgical implantation andconfiguration of a cardiac therapy device) may include each of the threemodes 150. In at least one embodiment, a system designed for use in aconsultation room of a medical care facility (e.g., for generalevaluation and consultation of a patient) may include the initialexamination mode 152 and the follow-up mode 156 but not the implantationmode 154.

An exemplary graphical interface (GUI) 160 for use in an initialexamination or consultation is depicted in FIG. 4. As shown, the GUI 160may include, among other things, a graphical representation 162 ofmeasured surrogate electrical activation times, metrics 170 of cardiachealth, and an indication 172 of whether cardiac therapy for the patientmay be beneficial. The initial examination may include applyingelectrode apparatus such as described herein with reference to FIGS. 1-2to a patient, measuring surrogate electrical activation times and ECGinformation using the electrode apparatus, and displaying the data forthe evaluation of the patient for cardiac therapy on the GUI 160.

The graphical representation 162 of measured surrogate cardiacelectrical activation times may be depicted in a variety of fashions. Asshown, the surrogate electrical activation times are shown as acolor-coded, or color-scaled, segment 168 extending over, or wrappedaround, a graphical representation of a human torso 164, 166. Morespecifically, an anterior side of a human torso 164 and a posterior sideof a human torso 166 are depicted, each including a color-coded segment168 graphically depicting surrogate electrical activation timesmeasured, e.g., using the electrical apparatus described herein withreference to FIGS. 1-2. Further, the graphical representation 162 ofmeasured surrogate cardiac electrical activation times shown on theanterior side of a human torso 164 may be measured using electrodeslocated on, or proximate to, the anterior side of the patient's torso,and likewise, the graphical representation 162 of measured surrogatecardiac electrical activation times shown on the posterior side of thehuman torso 166 may be measured using electrodes located on, orproximate to, the posterior side of the patient's torso. In other words,the graphical representation 162 of measured surrogate cardiacelectrical activation times shown on the anterior side of the humantorso 164 correlates to actual electrical signals measured usingelectrodes configured to measure electrical signals on the anterior sideof the patient's torso, and the graphical representation 162 of measuredsurrogate cardiac electrical activation times shown on the posteriorside of the human torso 166 correlates to actual electrical signalsmeasured using electrodes configured to measure electrical signals onthe posterior side of the patient's torso. The graphical representation162 further includes a color-coded scale 169 corresponding to thecolor-coded segments 168, to, e.g., provide basis for the coloring ofthe color-coded segments 168.

Additional exemplary graphical representations of surrogate electricalactivation times may be described in U.S. Patent Application PublicationNo. 2012/0284003 A1 published on Nov. 8, 2012 and entitled “AssessingIntra-Cardiac Activation Patterns” and U.S. Patent ApplicationPublication No. 2012/0283587 A1 published on Nov. 8, 2012 and entitled“Assessing Intra-Cardiac Activation Patterns and ElectricalDyssynchrony,” each of which are hereby incorporated by reference intheir entireties.

In other embodiments, the surrogate electrical activation times may becolor-coded across the entire graphical depiction of a human torsoand/or any smaller or larger part of human anatomy. Further, in at leastone embodiment, the graphical depictions of a human torso 164, 166 maybe actual images of the patient being evaluated. The surrogate cardiacelectrical activation times may be further depicted alphanumericallyover a graphical depiction of human anatomy. For example, a plurality ofsurrogate cardiac electrical activation times in milliseconds may begraphically overlaid over the torsos 164, 166.

In one or more embodiments, the graphical depiction of a portion ofhuman anatomy displayed on the exemplary graphical user interfaces mayinclude a graphical representation of a human heart. For example, aposterior side of a human heart 12 is depicted in FIG. 5 with surrogateelectrical activation times color-coded across the surface of the heart12. As shown, the posterolateral left ventricle region 165 shows lateactivation (e.g., about 150 milliseconds). In other embodiments, both aposterior and anterior side of a human heart may be graphically depictedand overlaid with electrical activation information.

The exemplary GUI 160 of FIG. 4 further includes metrics 170 of thepatient's cardiac health. As shown, the metrics 170 are QRS width andelectrical dyssynchrony, which both may be useful in the evaluation ofthe patient for cardiac therapy. Although in this embodiment, themetrics 170 include two metrics, it is to be understood that exemplarygraphical user interfaces may include one metric or more than twometrics related to the patient's cardiac health. For example, themetrics 170 may include one or more of a standard deviation, range,interquartile deviation, one or more statistical averages (e.g., mean,median, mode) of activation times of all electrodes or a subset ofelectrodes proximate a specific portion of anatomy (such as, e.g.,electrodes located at the left side of the patient that are surrogate ofthe left ventricle), one or more timing intervals between certainfiducial points (e.g., onset of depolarization to first negative orpositive peak on one or more electrocardiograms, etc.), etc. Further,the cardiac health metrics may include one or more metrics described inU.S. Provisional Patent Application No. 61/834,133 entitled “METRICS OFELECTRICAL DYSSYNCHRONY AND ELECTRICAL ACTIVATION PATTERNS FROM SURFACEECG ELECTRODES” and filed on Jun. 12, 2013, which is hereby incorporatedby reference it its entirety

The exemplary GUI 160 of FIG. 4 further includes an indication 172 ofwhether cardiac therapy for the patient may be beneficial. Theindication 172 of whether cardiac therapy for the patient may bebeneficial may be defined as a suggestion or recommendation based on themeasured electrical data from the electrode apparatus with respect to apotential cardiac therapy. In the exemplary GUI 160, the indication 172of whether cardiac therapy for the patient may be beneficial notes thefollowing: “POTENTIAL CRT BENEFIT=HIGH,” and thus, the indication 172indicates that this patient may have a high likelihood of benefitingfrom cardiac resynchronization therapy.

Additionally, the exemplary GUI 160 of FIG. 4 includes anelectrocardiogram area 174 that depicts one or more electrocardiogramsof the patient measured using the electrode apparatus. Although only oneelectrocardiogram is depicted in the electrocardiogram area 174, aplurality of electrocardiograms may be depicted in the electrocardiogramarea 174 and/or other areas of the GUI 160. Further, one or more (e.g.,a set or subset) of available electrocardiograms (e.g., measured usingdifferent electrodes or electrode sets located in different locationsabout a patient) may be selected by a user (e.g., physician) for viewingon the GUI 160. When the electrocardiogram area 174 includes more thanone electrocardiogram, the electrocardiograms may be time-aligned (e.g.,the electrograms may be aligned along the same time period, theelectrograms may be aligned by cardiac cycle, etc.). Additionally, eachelectrogram may cover either a single beat or multiple beats, which maybe selected or configured by a user. Further, the one or moreelectrocardiograms may be stored from a previous examination such that auser may compare previously-recorded electrocardiograms topresently-monitored electrocardiograms.

The data such as electrical activation time data, metrics of cardiachealth, electrocardiograms, etc. measured when using the initialexamination mode may be stored within the computing apparatus for use ata later time, e.g., to compare the patient's cardiac health beforecardiac therapy to after cardiac therapy, to adjust or configure cardiactherapy for a patient, etc. For example, the data collected during theinitial examination/consultation depicted in the initial examinationgraphical user interface 160 of FIG. 4 is used in the exemplaryimplantation graphical user interface 180 of FIG. 6 and the exemplaryfollow-up graphical user interface 220 of FIG. 8.

During implantation of a cardiac therapy device such, e.g., as a cardiacresynchronization therapy device, the exemplary systems, methods, andinterfaces may be configured to provide noninvasive evaluation of thecardiac therapy being implanted. An exemplary graphical interface (GUI)180 for use during implantation is depicted in FIG. 6. As shown, the GUI180 may include, among other things, graphical representations 181 ofpreviously-measured and presently measured surrogate electricalactivation times, previously-measured and presently-measured metrics184, 186 of cardiac health, and an indication 188 of whether the cardiactherapy appears to be beneficial. Although the surrogate electricalactivation times and cardiac health metrics are described as beingpreviously-measured or presently-measured, it is to be understood that“previously-measured” data is designed to encompass, or describe, anymeasurements prior to the “presently-measured” data, and, likewise,“presently-measured” data is designed to encompass, or describe, anymeasurements after to the “previously-measured” data. In one or moreembodiments, the “previously-measured” data may represent data measuredduring intrinsic rhythm before cardiac therapy (e.g., implantation of aCRT device). In other words, the “previously-measured” data mayrepresent baseline values. In one or more embodiments, the“previously-measured” data may represent data measured with cardiactherapy being disabled or before any adjustments or modifications aremade to cardiac therapy being presently delivered (e.g., by CRT device)and the “presently-measured” data may represent data measured after theadjustments or modifications are made.

Similar to the initial examination, electrode apparatus such asdescribed herein with reference to FIGS. 1-2 may be applied to apatient, surrogate electrical activation times and ECG information usingthe electrode apparatus may be measured, and the surrogate electricalactivation times and ECG information data may be displayed on the GUI180. In at least one embodiment, the GUI 180 may be described asproviding a before-and-after representation of the cardiac health of apatient before cardiac therapy and after cardiac therapy.

The graphical representations 181 of previously-measured and presentlymeasured surrogate electrical activation times include a graphicalrepresentation 182 of previously-measured surrogate electricalactivation times and a graphical representation 183 ofpresently-measured surrogate electrical activation times. As labeled onthe GUI 180, the graphical representation 182 of previously-measuredsurrogate electrical activation times represents the patient's intrinsicrhythm (e.g., without pacing, without cardiac therapy, etc.) and thegraphical representation 183 of presently-measured surrogate electricalactivation times represents the patient's paced rhythm. The graphicalrepresentations 182, 183 may be substantially similar to the graphicalrepresentation 162 of the GUI 160 described herein with reference toFIG. 4.

The GUI 180 further includes previously-measured metrics 184 of cardiachealth and presently-measured metrics 186 of cardiac health for thepatient such that a user may compare the values presented thereby to,e.g., evaluate the cardiac therapy being delivered. As shown, similar tothe initial examination GUI 160, the metrics 184, 186 include QRS widthand electrical dyssynchrony. As shown, the QRS width has increased by 10milliseconds and the electrical dyssynchrony has decreased 12milliseconds from the intrinsic data to the paced data, which may, e.g.,indicate that the cardiac therapy being delivered to the patient isbeneficial. The GUI 180 further includes an indication 188 of whetherthe cardiac therapy appears to be beneficial. In this example, theindication 188 notes: “LV LEAD LOCATION: GOOD Dyssynchrony improved by36%.” Although this indication 188 is based on an electricaldyssynchrony comparison between the previously-measured electricaldyssynchrony, other exemplary indications of whether cardiac therapyappears to be beneficial for a patient may include, or utilize,different data such as, e.g., comparisons of ECG waveform betweenpreviously measured ECG waveform shape (e.g., as may be described in“Analysis of Ventricular Activation Using Surface Electrocardiography toPredict Left Ventricular Reverse Volumetric Remodeling During CardiacResynchronization Therapy” by Sweeney, et al., Circulation:Arrhythmia/Electrophysiology, Feb. 9, 2010: pages 626-634, which isincorporated herein by reference in its entirety), changes in ECG vectorloop areas (e.g., as may be described in “Vectorcardiography as a Toolfor Easy Optimization of Cardiac Resynchronization Therapy in CanineLeft Bundle Branch Block Hearts” by van Deursen et al., Circulation:Arrhythmia/Electrophysiology, June 2012: pages 544-552, which isincorporated herein by reference in its entirety), changes in QRSduration, etc.

Additionally, the GUI 180 of FIG. 6 may include an electrocardiogramarea 189 similar to the electrocardiogram area 174 described herein withreference to FIG. 4. Further, the electrocardiogram area 189 may includeone or more presently- and/or previously-measured electrocardiograms,which may be selected by a user. When the electrocardiogram area 189includes more than one electrocardiogram, the electrocardiograms may betime-aligned as described herein.

A user (e.g., a physician) may use the GUI 180 during implantation of acardiac therapy device and/or in the configuration of the cardiactherapy device. For example, the user may use the GUI 180 to confirmthat the implanted cardiac therapy device (e.g., cardiacresynchronization therapy device) is providing beneficial therapy to thepatient. Additionally, the user may want to change one or more settingsof configurations of the cardiac therapy device while activelymonitoring whether the cardiac therapy is beneficial to the patient. Forexample, the user may want to change a pacing timing interval, change apacing vector, and/or change a pacing mode while actively monitoring thecardiac therapy using the GUI 180.

An exemplary method of noninvasive evaluation of cardiac therapy for apatient and configuration of cardiac therapy 200 using, e.g., GUI 180 ofFIG. 6, is depicted in FIG. 7. As shown, the method 200 may measureelectrical data using electrode apparatus 202 such as, e.g., electricalactivation times, electrocardiograms, etc. The electrical activationtimes may be displayed 204 on the GUI 180 such as the graphicaldepictions/representations of surrogate electrical activation timesabout a human anatomy portion. Further, the cardiac information/metricsbased on the measured electrical data may also be displayed 206 on theGUI 180 such as electrical dyssynchrony.

Based on the information displayed by the GUI 180, a user may decide tomodify the cardiac therapy 208. In at least one embodiment, the GUI 180may provide the interface to modify/program the cardiac therapy device(e.g., modify or adjust one or more various configurations, parameters,etc. of the cardiac therapy device). For example, as shown in FIG. 6,the GUI 180 may include a modify area, or button, 190 that, uponselection, may trigger or initiate another graphical user interface usedto modify or program the cardiac therapy device.

As described herein, a user may want to change a pacing timing interval210, change a pacing vector 212, and/or change a pacing mode 214. Thetiming intervals may include A-V intervals, V-V intervals, etc. for two,three, and/or four chambers of the heart (e.g., two or more of the rightatrium, the right ventricle, the left atrium, and the left ventricle)and/or timing intervals for multiple pulses delivered for a singlecardiac cycle to the right and left ventricle from different electrodes(e.g. RV electrode to LV1 electrode, LV1 electrode to LV2 electrode,etc.). Changing the pacing vector 212 may include changing one or moreelectrodes that may be used for various pacing vectors during theprogrammed therapy. For example, one electrode of a pacing vector may beswitched from a tip electrode to ring electrode. Further, any of one ormore pacing electrodes (e.g., electrodes located on leads,leadless/wireless electrodes, etc.) used in cardiac therapy systems maybe selected or changed for any pacing vector. Changing the pacing mode214 may include changing the type of pacing being provided. For example,a cardiac therapy device may be delivering LV-only pacing, and a usermay switch the LV-only pacing to bi-ventricular pacing. Similarly, apacing configuration may be changed to pace from a single locationwithin one chamber of the heart to pacing more than two or morelocations within that same chamber with or without programmed timingdelays.

After the user has adjusted or modified the cardiac therapy, thegraphical depiction 183 of the presently-measured activation times andthe presently-measured metrics 186 may be updated to reflect the resultsfrom the new adjustments or modifications to the cardiac therapy. Thus,a user may immediately know whether any adjustments or modificationshave appeared to benefit the patient.

Further, although the graphical depiction 182 of the previously-measuredactivation times and the previously-measured cardiac metrics 184 of theGUI 180 depicted in FIG. 6 show measurements from intrinsic rhythm, theGUI 180 could be configured (e.g., by user selection, etc.) to showpreviously-measured data that was measured or recorded prior to anyadjustments or modifications being made to the cardiac therapy. Stillfurther, the indication 188 of whether the cardiac therapy appears to bebeneficial may also be updated to reflect the change.

After implantation of a cardiac therapy device such, e.g., as a cardiacresynchronization therapy device, the exemplary systems, methods, andinterfaces may be configured to provide noninvasive evaluation of thecardiac therapy after implantation (e.g., days, weeks, months, years,etc. after implantation). An exemplary graphical interface (GUI) 220 foruse during a follow-up examination is depicted in FIG. 8. As shown, theGUI 220 may include graphical representations 221 of previously-measuredand presently measured surrogate electrical activation times,previously-measured and presently-measured metrics 224, 226 of cardiachealth, an indication 228 of whether the cardiac therapy appears to bebeneficial, electrocardiogram area 229, and a modify area/button 230that may be substantially similar to the graphical representations 181,previously-measured and presently measured metrics 184, 186, anindication 188, and electrocardiogram area 189, and modify area/button190 of the GUI 180 described herein with respect to FIG. 6. Theelectrocardiogram area 189 may be configured to depict a plurality ofdifferent electrocardiograms (e.g., time-aligned, etc.). For example,the electrocardiogram area 189 may display electrocardiographic waveformdata, such as several time-aligned single- or multiple beatelectrocardiographic waveforms from the same cardiac cycle(s) measuredfrom different electrode(s) around the patient's torso, which may beselected by a user.

The implantable electrodes that may be implanted using the exemplarysystems, methods, and graphical user interfaces described herein may beused with respect to the implantation and configuration an implantablemedical device (IMD) and/or one or more leads configured to be locatedproximate one or more portions of a patient's heart. For example, theexemplary systems, methods, and interfaces may be used in conjunctionwith an exemplary therapy system 10 described herein with reference toFIGS. 9-11.

FIG. 9 is a conceptual diagram illustrating an exemplary therapy system10 that may be used to deliver pacing therapy to a patient 14. Patient14 may, but not necessarily, be a human. The therapy system 10 mayinclude an implantable medical device 16 (IMD), which may be coupled toleads 18, 20, 22. The IMD 16 may be, e.g., an implantable pacemaker,cardioverter, and/or defibrillator, that provides electrical signals tothe heart 12 of the patient 14 via electrodes coupled to one or more ofthe leads 18, 20, 22 (e.g., electrodes that may be implanted inaccordance with the description herein, such as, with use of noninvasiveselection of implantation site regions).

The leads 18, 20, 22 extend into the heart 12 of the patient 14 to senseelectrical activity of the heart 12 and/or to deliver electricalstimulation to the heart 12. In the example shown in FIG. 15, the rightventricular (RV) lead 18 extends through one or more veins (not shown),the superior vena cava (not shown), and the right atrium 26, and intothe right ventricle 28. The left ventricular (LV) coronary sinus lead 20extends through one or more veins, the vena cava, the right atrium 26,and into the coronary sinus 30 to a region adjacent to the free wall ofthe left ventricle 32 of the heart 12. The right atrial (RA) lead 22extends through one or more veins and the vena cava, and into the rightatrium 26 of the heart 12.

The IMD 16 may sense, among other things, electrical signals attendantto the depolarization and repolarization of the heart 12 via electrodescoupled to at least one of the leads 18, 20, 22. The IMD 16 may beconfigured to determine or identify effective electrodes located on theleads 18, 20, 22 using the exemplary methods and processes describedherein. In some examples, the IMD 16 provides pacing therapy (e.g.,pacing pulses) to the heart 12 based on the electrical signals sensedwithin the heart 12. The IMD 16 may be operable to adjust one or moreparameters associated with the pacing therapy such as, e.g., AV delayand other various timings, pulse wide, amplitude, voltage, burst length,etc. Further, the IMD 16 may be operable to use various electrodeconfigurations to deliver pacing therapy, which may be unipolar,bipolar, quadripoloar, or further multipolar. For example, a multipolarlead may include several electrodes that can be used for deliveringpacing therapy. Hence, a multipolar lead system may provide, or offer,multiple electrical vectors to pace from. A pacing vector may include atleast one cathode, which may be at least one electrode located on atleast one lead, and at least one anode, which may be at least oneelectrode located on at least one lead (e.g., the same lead, or adifferent lead) and/or on the casing, or can, of the IMD. Whileimprovement in cardiac function as a result of the pacing therapy mayprimarily depend on the cathode, the electrical parameters likeimpedance, pacing threshold voltage, current drain, longevity, etc. maybe more dependent on the pacing vector, which includes both the cathodeand the anode. The IMD 16 may also provide defibrillation therapy and/orcardioversion therapy via electrodes located on at least one of theleads 18, 20, 22. Further, the IMD 16 may detect arrhythmia of the heart12, such as fibrillation of the ventricles 28, 32, and deliverdefibrillation therapy to the heart 12 in the form of electrical pulses.In some examples, IMD 16 may be programmed to deliver a progression oftherapies, e.g., pulses with increasing energy levels, until afibrillation of heart 12 is stopped.

FIGS. 10A-10B are conceptual diagrams illustrating the IMD 16 and theleads 18, 20, 22 of therapy system 10 of FIG. 15 in more detail. Theleads 18, 20, 22 may be electrically coupled to a therapy deliverymodule (e.g., for delivery of pacing therapy), a sensing module (e.g.,for sensing one or more signals from one or more electrodes), and/or anyother modules of the IMD 16 via a connector block 34. In some examples,the proximal ends of the leads 18, 20, 22 may include electricalcontacts that electrically couple to respective electrical contactswithin the connector block 34 of the IMD 16. In addition, in someexamples, the leads 18, 20, 22 may be mechanically coupled to theconnector block 34 with the aid of set screws, connection pins, oranother suitable mechanical coupling mechanism.

Each of the leads 18, 20, 22 includes an elongated insulative lead body,which may carry a number of conductors (e.g., concentric coiledconductors, straight conductors, etc.) separated from one another byinsulation (e.g., tubular insulative sheaths). In the illustratedexample, bipolar electrodes 40, 42 are located proximate to a distal endof the lead 18. In addition, the bipolar electrodes 44, 45, 46, 47 arelocated proximate to a distal end of the lead 20 and the bipolarelectrodes 48, 50 are located proximate to a distal end of the lead 22.

The electrodes 40, 44, 44, 45, 46, 47, 48 may take the form of ringelectrodes, and the electrodes 42, 50 may take the form of extendablehelix tip electrodes mounted retractably within the insulative electrodeheads 52, 54, 56, respectively. Each of the electrodes 40, 42, 44, 45,46, 47, 48, 50 may be electrically coupled to a respective one of theconductors (e.g., coiled and/or straight) within the lead body of itsassociated lead 18, 20, 22, and thereby coupled to respective ones ofthe electrical contacts on the proximal end of the leads 18, 20, 22.

Additionally, electrodes 44, 45, 46 and 47 may have an electrode surfacearea of about 5.3 mm² to about 5.8 mm². Electrodes 44, 45, 46, and 47may also be referred to as LV1, LV2, LV3, and LV4, respectively. The LVelectrodes (i.e., left ventricle electrode 1 (LV1) 44, left ventricleelectrode 2 (LV2) 45, left ventricle electrode 3 (LV3) 46, and leftventricle 4 (LV4) 47 etc.) on the lead 20 can be spaced apart atvariable distances. For example, electrode 44 may be a distance of,e.g., about 21 millimeters (mm), away from electrode 45, electrodes 45and 46 may be spaced a distance of, e.g. about 1.3 mm to about 1.5 mm,away from each other, and electrodes 46 and 47 may be spaced a distanceof, e.g. 20 mm to about 21 mm, away from each other.

The electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58 may further be used tosense electrical signals (e.g., morphological waveforms withinelectrograms (EGM)) attendant to the depolarization and repolarizationof the heart 12. The sensed electrical signals may be used to determinewhich of the electrodes 40, 42, 44, 45, 46, 47, 48, 50 are the mosteffective in improving cardiac function. The electrical signals areconducted to the IMD 16 via the respective leads 18, 20, 22. In someexamples, the IMD 16 may also deliver pacing pulses via the electrodes40, 42, 44, 45, 46, 47, 48, 50 to cause depolarization of cardiac tissueof the patient's heart 12. In some examples, as illustrated in FIG. 10A,the IMD 16 includes one or more housing electrodes, such as housingelectrode 58, which may be formed integrally with an outer surface of ahousing 60 (e.g., hermetically-sealed housing) of the IMD 16 orotherwise coupled to the housing 60. Any of the electrodes 40, 42, 44,45, 46, 47, 48 and 50 may be used for unipolar sensing or pacing incombination with housing electrode 58. In other words, any of electrodes40, 42, 44, 45, 46, 47, 48, 50, 58 may be used in combination to form asensing vector, e.g., a sensing vector that may be used to evaluateand/or analyze the effectiveness of pacing therapy. It is generallyunderstood by those skilled in the art that other electrodes can also beselected to define, or be used for, pacing and sensing vectors. Further,any of electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, which are notbeing used to deliver pacing therapy, may be used to sense electricalactivity during pacing therapy.

As described in further detail with reference to FIG. 10A, the housing60 may enclose a therapy delivery module that may include a stimulationgenerator for generating cardiac pacing pulses and defibrillation orcardioversion shocks, as well as a sensing module for monitoring thepatient's heart rhythm. The leads 18, 20, 22 may also include elongatedelectrodes 62, 64, 66, respectively, which may take the form of a coil.The IMD 16 may deliver defibrillation shocks to the heart 12 via anycombination of the elongated electrodes 62, 64, 66 and the housingelectrode 58. The electrodes 58, 62, 64, 66 may also be used to delivercardioversion pulses to the heart 12. Further, the electrodes 62, 64, 66may be fabricated from any suitable electrically conductive material,such as, but not limited to, platinum, platinum alloy, and/or othermaterials known to be usable in implantable defibrillation electrodes.Since electrodes 62, 64, 66 are not generally configured to deliverpacing therapy, any of electrodes 62, 64, 66 may be used to senseelectrical activity (e.g., for use in determining electrodeeffectiveness, for use in analyzing pacing therapy effectiveness, etc.)and may be used in combination with any of electrodes 40, 42, 44, 45,46, 47, 48, 50, 58. In at least one embodiment, the RV elongatedelectrode 62 may be used to sense electrical activity of a patient'sheart during the delivery of pacing therapy (e.g., in combination withthe housing electrode 58 forming a RV elongated coil, or defibrillationelectrode-to-housing electrode vector).

The configuration of the exemplary therapy system 10 illustrated inFIGS. 9-11 is merely one example. In other examples, the therapy systemmay include epicardial leads and/or patch electrodes instead of or inaddition to the transvenous leads 18, 20, 22 illustrated in FIG. 9.Additionally, in other examples, the therapy system 10 may be implantedin/around the cardiac space without transvenous leads (e.g.,leadless/wireless pacing systems) or with leads implanted (e.g.,implanted transvenously or using approaches) into the left chambers ofthe heart (in addition to or replacing the transvenous leads placed intothe right chambers of the heart as illustrated in FIG. 9). Further, inone or more embodiments, the IMD 16 need not be implanted within thepatient 14. For example, the IMD 16 may deliver various cardiactherapies to the heart 12 via percutaneous leads that extend through theskin of the patient 14 to a variety of positions within or outside ofthe heart 12. In one or more embodiments, the system 10 may utilizewireless pacing (e.g., using energy transmission to the intracardiacpacing component(s) via ultrasound, inductive coupling, RF, etc.) andsensing cardiac activation using electrodes on the can/housing and/or onsubcutaneous leads.

In other examples of therapy systems that provide electrical stimulationtherapy to the heart 12, such therapy systems may include any suitablenumber of leads coupled to the IMD 16, and each of the leads may extendto any location within or proximate to the heart 12. For example, otherexamples of therapy systems may include three transvenous leads locatedas illustrated in FIGS. 9-11. Still further, other therapy systems mayinclude a single lead that extends from the IMD 16 into the right atrium26 or the right ventricle 28, or two leads that extend into a respectiveone of the right atrium 26 and the right ventricle 28.

FIG. 11A is a functional block diagram of one exemplary configuration ofthe IMD 16. As shown, the IMD 16 may include a control module 81, atherapy delivery module 84 (e.g., which may include a stimulationgenerator), a sensing module 86, and a power source 90.

The control module 81 may include a processor 80, memory 82, and atelemetry module 88. The memory 82 may include computer-readableinstructions that, when executed, e.g., by the processor 80, cause theIMD 16 and/or the control module 81 to perform various functionsattributed to the IMD 16 and/or the control module 81 described herein.Further, the memory 82 may include any volatile, non-volatile, magnetic,optical, and/or electrical media, such as a random access memory (RAM),read-only memory (ROM), non-volatile RAM (NVRAM), electrically-erasableprogrammable ROM (EEPROM), flash memory, and/or any other digital media.An exemplary capture management module may be the left ventricularcapture management (LVCM) module described in U.S. Pat. No. 7,684,863entitled “LV THRESHOLD MEASUREMENT AND CAPTURE MANAGEMENT” and issuedMar. 23, 2010, which is incorporated herein by reference in itsentirety.

The processor 80 of the control module 81 may include any one or more ofa microprocessor, a controller, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field-programmablegate array (FPGA), and/or equivalent discrete or integrated logiccircuitry. In some examples, the processor 80 may include multiplecomponents, such as any combination of one or more microprocessors, oneor more controllers, one or more DSPs, one or more ASICs, and/or one ormore FPGAs, as well as other discrete or integrated logic circuitry. Thefunctions attributed to the processor 80 herein may be embodied assoftware, firmware, hardware, or any combination thereof.

The control module 81 may be used to determine the effectiveness of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 using theexemplary methods and/or processes described herein according to aselected one or more programs, which may be stored in the memory 82.Further, the control module 81 may control the therapy delivery module84 to deliver therapy (e.g., electrical stimulation therapy such aspacing) to the heart 12 according to a selected one or more therapyprograms, which may be stored in the memory 82. More, specifically, thecontrol module 81 (e.g., the processor 80) may control variousparameters of the electrical stimulus delivered by the therapy deliverymodule 84 such as, e.g., AV delays, pacing pulses with the amplitudes,pulse widths, frequency, or electrode polarities, etc., which may bespecified by one or more selected therapy programs (e.g., AV delayadjustment programs, pacing therapy programs, pacing recovery programs,capture management programs, etc.). As shown, the therapy deliverymodule 84 is electrically coupled to electrodes 40, 42, 44, 45, 46, 47,48, 50, 58, 62, 64, 66, e.g., via conductors of the respective lead 18,20, 22, or, in the case of housing electrode 58, via an electricalconductor disposed within housing 60 of IMD 16. Therapy delivery module84 may be configured to generate and deliver electrical stimulationtherapy such as pacing therapy to the heart 12 using one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66.

For example, therapy delivery module 84 may deliver pacing stimulus(e.g., pacing pulses) via ring electrodes 40, 44, 45, 46, 47, 48 coupledto leads 18, 20, and 22, respectively, and/or helical tip electrodes 42and 50 of leads 18 and 22. Further, for example, therapy delivery module84 may deliver defibrillation shocks to heart 12 via at least two ofelectrodes 58, 62, 64, 66. In some examples, therapy delivery module 84may be configured to deliver pacing, cardioversion, or defibrillationstimulation in the form of electrical pulses. In other examples, therapydelivery module 84 may be configured deliver one or more of these typesof stimulation in the form of other signals, such as sine waves, squarewaves, and/or other substantially continuous time signals.

The IMD 16 may further include a switch module 85 and the control module81 (e.g., the processor 80) may use the switch module 85 to select,e.g., via a data/address bus, which of the available electrodes are usedto deliver therapy such as pacing pulses for pacing therapy, or which ofthe available electrodes are used for sensing. The switch module 85 mayinclude a switch array, switch matrix, multiplexer, or any other type ofswitching device suitable to selectively couple the sensing module 86and/or the therapy delivery module 84 to one or more selectedelectrodes. More specifically, the therapy delivery module 84 mayinclude a plurality of pacing output circuits. Each pacing outputcircuit of the plurality of pacing output circuits may be selectivelycoupled, e.g., using the switch module 85, to one or more of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 (e.g., a pairof electrodes for delivery of therapy to a pacing vector). In otherwords, each electrode can be selectively coupled to one of the pacingoutput circuits of the therapy delivery module using the switchingmodule 85.

The sensing module 86 is coupled (e.g., electrically coupled) to sensingapparatus, which may include, among additional sensing apparatus, theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66 to monitorelectrical activity of the heart 12, e.g., electrocardiogram(ECG)/electrogram (EGM) signals, etc. The ECG/EGM signals may be used tomeasure or monitor activation times (e.g., ventricular activationstimes, etc.), heart rate (HR), heart rate variability (HRV), heart rateturbulence (HRT), deceleration/acceleration capacity, decelerationsequence incidence, T-wave alternans (TWA), P-wave to P-wave intervals(also referred to as the P-P intervals or A-A intervals), R-wave toR-wave intervals (also referred to as the R-R intervals or V-Vintervals), P-wave to QRS complex intervals (also referred to as the P-Rintervals, A-V intervals, or P-Q intervals), QRS-complex morphology, STsegment (i.e., the segment that connects the QRS complex and theT-wave), T-wave changes, QT intervals, electrical vectors, etc.

The switch module 85 may be also be used with the sensing module 86 toselect which of the available electrodes are used, or enabled, to, e.g.,sense electrical activity of the patient's heart (e.g., one or moreelectrical vectors of the patient's heart using any combination of theelectrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62, 64, 66). Likewise,the switch module 85 may be also be used with the sensing module 86 toselect which of the available electrodes are not to be used (e.g.,disabled) to, e.g., sense electrical activity of the patient's heart(e.g., one or more electrical vectors of the patient's heart using anycombination of the electrodes 40, 42, 44, 45, 46, 47, 48, 50, 58, 62,64, 66), etc. In some examples, the control module 81 may select theelectrodes that function as sensing electrodes via the switch modulewithin the sensing module 86, e.g., by providing signals via adata/address bus.

In some examples, sensing module 86 includes a channel that includes anamplifier with a relatively wider pass band than the R-wave or P-waveamplifiers. Signals from the selected sensing electrodes may be providedto a multiplexer, and thereafter converted to multi-bit digital signalsby an analog-to-digital converter for storage in memory 82, e.g., as anelectrogram (EGM). In some examples, the storage of such EGMs in memory82 may be under the control of a direct memory access circuit.

In some examples, the control module 81 may operate as an interruptdriven device, and may be responsive to interrupts from pacer timing andcontrol module, where the interrupts may correspond to the occurrencesof sensed P-waves and R-waves and the generation of cardiac pacingpulses. Any necessary mathematical calculations may be performed by theprocessor 80 and any updating of the values or intervals controlled bythe pacer timing and control module may take place following suchinterrupts. A portion of memory 82 may be configured as a plurality ofrecirculating buffers, capable of holding one or more series of measuredintervals, which may be analyzed by, e.g., the processor 80 in responseto the occurrence of a pace or sense interrupt to determine whether thepatient's heart 12 is presently exhibiting atrial or ventriculartachyarrhythmia.

The telemetry module 88 of the control module 81 may include anysuitable hardware, firmware, software, or any combination thereof forcommunicating with another device, such as a programmer. For example,under the control of the processor 80, the telemetry module 88 mayreceive downlink telemetry from and send uplink telemetry to aprogrammer with the aid of an antenna, which may be internal and/orexternal. The processor 80 may provide the data to be uplinked to aprogrammer and the control signals for the telemetry circuit within thetelemetry module 88, e.g., via an address/data bus. In some examples,the telemetry module 88 may provide received data to the processor 80via a multiplexer.

The various components of the IMD 16 are further coupled to a powersource 90, which may include a rechargeable or non-rechargeable battery.A non-rechargeable battery may be selected to last for several years,while a rechargeable battery may be inductively charged from an externaldevice, e.g., on a daily or weekly basis.

FIG. 11B is another embodiment of a functional block diagram for IMD 16.FIG. 11B depicts bipolar RA lead 22, bipolar RV lead 18, and bipolar LVCS lead 20 without the LA CS pace/sense electrodes and coupled with animplantable pulse generator (IPG) circuit 31 having programmable modesand parameters of a bi-ventricular DDD/R type known in the pacing art.In turn, the sensor signal processing circuit 91 indirectly couples tothe timing circuit 83 and via data and control bus to microcomputercircuitry 33. The IPG circuit 31 is illustrated in a functional blockdiagram divided generally into a microcomputer circuit 33 and a pacingcircuit 21. The pacing circuit 21 includes the digital controller/timercircuit 83, the output amplifiers circuit 51, the sense amplifierscircuit 55, the RF telemetry transceiver 41, the activity sensor circuit35 as well as a number of other circuits and components described below.

Crystal oscillator circuit 89 provides the basic timing clock for thepacing circuit 21, while battery 29 provides power. Power-on-resetcircuit 87 responds to initial connection of the circuit to the batteryfor defining an initial operating condition and similarly, resets theoperative state of the device in response to detection of a low batterycondition. Reference mode circuit 37 generates stable voltage referenceand currents for the analog circuits within the pacing circuit 21, whileanalog to digital converter ADC and multiplexer circuit 39 digitizesanalog signals and voltage to provide real time telemetry if a cardiacsignals from sense amplifiers 55, for uplink transmission via RFtransmitter and receiver circuit 41. Voltage reference and bias circuit37, ADC and multiplexer 39, power-on-reset circuit 87 and crystaloscillator circuit 89 may correspond to any of those presently used incurrent marketed implantable cardiac pacemakers.

If the IPG is programmed to a rate responsive mode, the signals outputby one or more physiologic sensor are employed as a rate controlparameter (RCP) to derive a physiologic escape interval. For example,the escape interval is adjusted proportionally to the patient's activitylevel developed in the patient activity sensor (PAS) circuit 35 in thedepicted, exemplary IPG circuit 31. The patient activity sensor 27 iscoupled to the IPG housing and may take the form of a piezoelectriccrystal transducer as is well known in the art and its output signal isprocessed and used as the RCP. Sensor 27 generates electrical signals inresponse to sensed physical activity that are processed by activitycircuit 35 and provided to digital controller/timer circuit 83. Activitycircuit 35 and associated sensor 27 may correspond to the circuitrydisclosed in U.S. Pat. No. 5,052,388 entitled “METHOD AND APPARATUS FORIMPLEMENTING ACTIVITY SENSING IN A PULSE GENERATOR” and issued on Oct.1, 1991 and U.S. Pat. No. 4,428,378 entitled “RATE ADAPTIVE PACER” andissued on Jan. 31, 1984, each of which are incorporated herein byreference in their entireties. Similarly, the exemplary systems,apparatus, and methods described herein may be practiced in conjunctionwith alternate types of sensors such as oxygenation sensors, pressuresensors, pH sensors and respiration sensors, all well known for use inproviding rate responsive pacing capabilities. Alternately, QT time maybe used as the rate indicating parameter, in which case no extra sensoris required. Similarly, the exemplary embodiments described herein mayalso be practiced in non-rate responsive pacemakers.

Data transmission to and from the external programmer is accomplished byway of the telemetry antenna 57 and an associated RF transceiver 41,which serves both to demodulate received downlink telemetry and totransmit uplink telemetry. Uplink telemetry capabilities will typicallyinclude the ability to transmit stored digital information, e.g.operating modes and parameters, EGM histograms, and other events, aswell as real time EGMs of atrial and/or ventricular electrical activityand marker channel pulses indicating the occurrence of sensed and paceddepolarizations in the atrium and ventricle, as are well known in thepacing art.

Microcomputer 33 contains a microprocessor 80 and associated systemclock and on-processor RAM and ROM chips 82A and 82B, respectively. Inaddition, microcomputer circuit 33 includes a separate RAM/ROM chip 82Cto provide additional memory capacity. Microprocessor 80 normallyoperates in a reduced power consumption mode and is interrupt driven.Microprocessor 80 is awakened in response to defined interrupt events,which may include A-TRIG, RV-TRIG, LV-TRIG signals generated by timersin digital timer/controller circuit 83 and A-EVENT, RV-EVENT, andLV-EVENT signals generated by sense amplifiers circuit 55, among others.The specific values of the intervals and delays timed out by digitalcontroller/timer circuit 83 are controlled by the microcomputer circuit33 by way of data and control bus from programmed-in parameter valuesand operating modes. In addition, if programmed to operate as a rateresponsive pacemaker, a timed interrupt, e.g., every cycle or every twoseconds, may be provided in order to allow the microprocessor to analyzethe activity sensor data and update the basic A-A, V-A, or V-V escapeinterval, as applicable. In addition, the microprocessor 80 may alsoserve to define variable, operative AV delay intervals and the energydelivered to each ventricle.

In one embodiment, microprocessor 80 is a custom microprocessor adaptedto fetch and execute instructions stored in RAM/ROM unit 82 in aconventional manner. It is contemplated, however, that otherimplementations may be suitable to practice the present invention. Forexample, an off-the-shelf, commercially available microprocessor ormicrocontroller, or custom application-specific, hardwired logic, orstate-machine type circuit may perform the functions of microprocessor80.

Digital controller/timer circuit 83 operates under the general controlof the microcomputer 33 to control timing and other functions within thepacing circuit 320 and includes a set of timing and associated logiccircuits of which certain ones pertinent to the present invention aredepicted. The depicted timing circuits include URI/LRI timers 83A, V-Vdelay timer 83B, intrinsic interval timers 83C for timing elapsedV-EVENT to V-EVENT intervals or V-EVENT to A-EVENT intervals or the V-Vconduction interval, escape interval timers 83D for timing A-A, V-A,and/or V-V pacing escape intervals, an AV delay interval timer 83E fortiming the A-LVp delay (or A-RVp delay) from a preceding A-EVENT orA-TRIG, a post-ventricular timer 83F for timing post-ventricular timeperiods, and a date/time clock 83G.

The AV delay interval timer 83E is loaded with an appropriate delayinterval for one ventricular chamber (e.g., either an A-RVp delay or anA-LVp delay as determined using known methods) to time-out starting froma preceding A-PACE or A-EVENT. The interval timer 83E triggers pacingstimulus delivery, and can be based on one or more prior cardiac cycles(or from a data set empirically derived for a given patient).

The post-event timer 83F time out the post-ventricular time periodfollowing an RV-EVENT or LV-EVENT or a RV-TRIG or LV-TRIG andpost-atrial time periods following an A-EVENT or A-TRIG. The durationsof the post-event time periods may also be selected as programmableparameters stored in the microcomputer 33. The post-ventricular timeperiods include the PVARP, a post-atrial ventricular blanking period(PAVBP), a ventricular blanking period (VBP), a post-ventricular atrialblanking period (PVARP) and a ventricular refractory period (VRP)although other periods can be suitably defined depending, at least inpart, on the operative circuitry employed in the pacing engine. Thepost-atrial time periods include an atrial refractory period (ARP)during which an A-EVENT is ignored for the purpose of resetting any AVdelay, and an atrial blanking period (ABP) during which atrial sensingis disabled. It should be noted that the starting of the post-atrialtime periods and the AV delays can be commenced substantiallysimultaneously with the start or end of each A-EVENT or A-TRIG or, inthe latter case, upon the end of the A-PACE which may follow the A-TRIG.Similarly, the starting of the post-ventricular time periods and the V-Aescape interval can be commenced substantially simultaneously with thestart or end of the V-EVENT or V-TRIG or, in the latter case, upon theend of the V-PACE which may follow the V-TRIG. The microprocessor 80also optionally calculates AV delays, post-ventricular time periods, andpost-atrial time periods that vary with the sensor based escape intervalestablished in response to the RCP(s) and/or with the intrinsic atrialrate.

The output amplifiers circuit 51 contains a RA pace pulse generator (anda LA pace pulse generator if LA pacing is provided), a RV pace pulsegenerator, and a LV pace pulse generator or corresponding to any ofthose presently employed in commercially marketed cardiac pacemakersproviding atrial and ventricular pacing. In order to trigger generationof an RV-PACE or LV-PACE pulse, digital controller/timer circuit 83generates the RV-TRIG signal at the time-out of the A-RVp delay (in thecase of RV pre-excitation) or the LV-TRIG at the time-out of the A-LVpdelay (in the case of LV pre-excitation) provided by AV delay intervaltimer 83E (or the V-V delay timer 83B). Similarly, digitalcontroller/timer circuit 83 generates an RA-TRIG signal that triggersoutput of an RA-PACE pulse (or an LA-TRIG signal that triggers output ofan LA-PACE pulse, if provided) at the end of the V-A escape intervaltimed by escape interval timers 83D.

The output amplifiers circuit 51 includes switching circuits forcoupling selected pace electrode pairs from among the lead conductorsand the IND CAN electrode 20 to the RA pace pulse generator (and LA pacepulse generator if provided), RV pace pulse generator and LV pace pulsegenerator. Pace/sense electrode pair selection and control circuit 53selects lead conductors and associated pace electrode pairs to becoupled with the atrial and ventricular output amplifiers within outputamplifiers circuit 51 for accomplishing RA, LA, RV and LV pacing.

The sense amplifiers circuit 55 contains sense amplifiers correspondingto any of those presently employed in contemporary cardiac pacemakersfor atrial and ventricular pacing and sensing. High impedance P-wave andR-wave sense amplifiers may be used to amplify a voltage differencesignal that is generated across the sense electrode pairs by the passageof cardiac depolarization wavefronts. The high impedance senseamplifiers use high gain to amplify the low amplitude signals and relyon pass band filters, time domain filtering and amplitude thresholdcomparison to discriminate a P-wave or R-wave from background electricalnoise. Digital controller/timer circuit 83 controls sensitivity settingsof the atrial and ventricular sense amplifiers 55.

The sense amplifiers are typically uncoupled from the sense electrodesduring the blanking periods before, during, and after delivery of a pacepulse to any of the pace electrodes of the pacing system to avoidsaturation of the sense amplifiers. The sense amplifiers circuit 55includes blanking circuits for uncoupling the selected pairs of the leadconductors and the IND-CAN electrode 20 from the inputs of the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier during the ABP, PVABP and VBP. The sense amplifierscircuit 55 also includes switching circuits for coupling selected senseelectrode lead conductors and the IND-CAN electrode 20 to the RA senseamplifier (and LA sense amplifier if provided), RV sense amplifier andLV sense amplifier. Again, sense electrode selection and control circuit53 selects conductors and associated sense electrode pairs to be coupledwith the atrial and ventricular sense amplifiers within the outputamplifiers circuit 51 and sense amplifiers circuit 55 for accomplishingRA, LA, RV and LV sensing along desired unipolar and bipolar sensingvectors.

Right atrial depolarizations or P-waves in the RA-SENSE signal that aresensed by the RA sense amplifier result in a RA-EVENT signal that iscommunicated to the digital controller/timer circuit 83. Similarly, leftatrial depolarizations or P-waves in the LA-SENSE signal that are sensedby the LA sense amplifier, if provided, result in a LA-EVENT signal thatis communicated to the digital controller/timer circuit 83. Ventriculardepolarizations or R-waves in the RV-SENSE signal are sensed by aventricular sense amplifier result in an RV-EVENT signal that iscommunicated to the digital controller/timer circuit 83. Similarly,ventricular depolarizations or R-waves in the LV-SENSE signal are sensedby a ventricular sense amplifier result in an LV-EVENT signal that iscommunicated to the digital controller/timer circuit 83. The RV-EVENT,LV-EVENT, and RA-EVENT, LA-SENSE signals may be refractory ornon-refractory, and can inadvertently be triggered by electrical noisesignals or aberrantly conducted depolarization waves rather than trueR-waves or P-waves.

The techniques described in this disclosure, including those attributedto the IMD 16, the computing apparatus 140, and/or various constituentcomponents, may be implemented, at least in part, in hardware, software,firmware, or any combination thereof. For example, various aspects ofthe techniques may be implemented within one or more processors,including one or more microprocessors, DSPs, ASICs, FPGAs, or any otherequivalent integrated or discrete logic circuitry, as well as anycombinations of such components, embodied in programmers, such asphysician or patient programmers, stimulators, image processing devices,or other devices. The term “module,” “processor,” or “processingcircuitry” may generally refer to any of the foregoing logic circuitry,alone or in combination with other logic circuitry, or any otherequivalent circuitry.

Such hardware, software, and/or firmware may be implemented within thesame device or within separate devices to support the various operationsand functions described in this disclosure. In addition, any of thedescribed units, modules, or components may be implemented together orseparately as discrete but interoperable logic devices. Depiction ofdifferent features as modules or units is intended to highlightdifferent functional aspects and does not necessarily imply that suchmodules or units must be realized by separate hardware or softwarecomponents. Rather, functionality associated with one or more modules orunits may be performed by separate hardware or software components, orintegrated within common or separate hardware or software components.

When implemented in software, the functionality ascribed to the systems,devices and techniques described in this disclosure may be embodied asinstructions on a computer-readable medium such as RAM, ROM, NVRAM,EEPROM, FLASH memory, magnetic data storage media, optical data storagemedia, or the like. The instructions may be executed by one or moreprocessors to support one or more aspects of the functionality describedin this disclosure.

This disclosure has been provided with reference to illustrativeembodiments and is not meant to be construed in a limiting sense. Asdescribed previously, one skilled in the art will recognize that othervarious illustrative applications may use the techniques as describedherein to take advantage of the beneficial characteristics of theapparatus and methods described herein. Various modifications of theillustrative embodiments, as well as additional embodiments of thedisclosure, will be apparent upon reference to this description.

1.-20. (canceled)
 21. A system for assisting in noninvasive evaluationof a patient for cardiac therapy comprising: electrode apparatuscomprising a plurality of external surface electrodes positioned in anarray, wherein the electrode apparatus is configured to locate theplurality of external surface electrodes proximate the skin of thepatient; a display apparatus comprising a graphical user interfaceconfigured to present cardiac electrical activation time information andcardiac health information; and computing apparatus coupled to theelectrode apparatus and the display apparatus and configured to providethe graphical user interface displayed on the display apparatus toassist a user in noninvasively evaluating the patient for cardiactherapy, wherein the computing apparatus is further configured to:noninvasively measure surrogate cardiac electrical activation timesusing one or more external surface electrodes of the plurality ofexternal surface electrodes of the electrode apparatus proximate thepatient's skin and proximate the patient's heart without use of animplantable device, wherein the surrogate cardiac electrical activationtimes are representative of depolarization of cardiac tissue thatpropagates through the torso of the patient, display, on the graphicaluser interface, a map of electrical activation based on the measuredsurrogate cardiac electrical activation times that were noninvasivelymeasured using the one or more external surface electrodes of theplurality of external surface electrodes proximate the skin of thepatient without use of an implantable device, noninvasively measure atleast one metric of the patient's cardiac health using one or moreexternal surface electrodes of the plurality of external surfaceelectrodes of the electrode apparatus proximate the patient's skin andproximate the patient's heart without use of an implantable device, anddisplay, on the graphical user interface, the at least one metric of thepatient's cardiac health that was noninvasively measured using the oneor more external surface electrodes of the plurality of external surfaceelectrodes proximate the skin of the patient without use of animplantable device.
 22. The system of claim 21, wherein the at least onemetric comprises QRS width.
 23. The system of claim 21, wherein the atleast one metric comprises a standard deviation of the surrogate cardiacelectrical activation times.
 24. The system of claim 21, wherein the atleast one metric comprises a standard deviation of a subset of thesurrogate cardiac electrical activation times.
 25. The system of claim24, wherein the subset of the surrogate cardiac electrical activationtimes corresponds to a subset of the external electrodes located at aleft side of the patient that are surrogate of the left ventricle. 26.The system of claim 21, wherein displaying the graphical depiction ofthe measured surrogate cardiac electrical activation times comprises:displaying an anterior graphical depiction of the measured surrogatecardiac electrical activation times corresponding to an anterior subsetof the external electrodes located at an anterior of the patient; anddisplaying a posterior graphical depiction of the measured surrogatecardiac electrical activation times corresponding to a posterior subsetof the external electrodes located at a posterior of the patient. 27.The system of claim 21, wherein displaying the graphical depiction ofthe measured surrogate cardiac electrical activation times comprisesdisplaying a graphical depiction of the measured surrogate cardiacelectrical activation times about a graphical depiction of at least oneof an anterior side of a human torso and a posterior side of a humantorso.
 28. The system of claim 21, wherein displaying the graphicaldepiction of the measured surrogate cardiac electrical activation timescomprises displaying a graphical depiction of the measured surrogatecardiac electrical activation times about a graphical depiction of atleast one of an anterior side of a heart and a posterior side of aheart.
 29. The system of claim 21, wherein the computing apparatus isfurther configured to display, on the graphical user interface, at leastone electrocardiogram of the patient, wherein each of the at least oneelectrocardiogram are captured using at least one different electrode,and wherein the at least one electrocardiogram is time-aligned on thegraphical user interface.
 30. The system of claim 21, wherein theplurality of external surface electrodes are configured to be locatedproximate the skin of the torso of the patient.
 31. Acomputer-implemented method for assisting in noninvasive evaluation of apatient for cardiac therapy, the method comprising: noninvasivelymeasuring surrogate cardiac electrical activation times using one ormore external surface electrodes proximate the skin of a patient andproximate the patient's heart without use of an implantable device,wherein the surrogate cardiac electrical activation times arerepresentative of depolarization of cardiac tissue that propagatesthrough the torso of the patient; displaying, on a graphical userinterface, a graphical depiction of a portion of human anatomy and a mapof electrical activation about the portion of human anatomy based on themeasured surrogate cardiac electrical activation times that werenoninvasively measured using the one or more external surface electrodesproximate the skin of the patient without use of an implantable device;noninvasively measuring at least one metric of the patient's cardiachealth using one or more external surface electrodes proximate the skinof a patient and proximate the patient's heart without use of animplantable device; and displaying, on the graphical user interface, theat least one metric of the patient's cardiac health that wasnoninvasively measured using the one or more external surface electrodesproximate the skin of the patient without use of an implantable device.32. The method of claim 31, wherein the at least one metric comprisesQRS width.
 33. The method of claim 31, wherein the at least one metriccomprises a standard deviation of the surrogate cardiac electricalactivation times.
 34. The method of claim 31, wherein the at least onemetric comprises a standard deviation of a subset of the surrogatecardiac electrical activation times.
 35. The method of claim 34, whereinthe subset of the surrogate cardiac electrical activation timescorresponds to a subset of the external electrodes located at a leftside of the patient that are surrogate of the left ventricle.
 36. Themethod of claim 31, wherein displaying the graphical depiction of themeasured surrogate cardiac electrical activation times comprises:displaying an anterior graphical depiction of the measured surrogatecardiac electrical activation times corresponding to an anterior subsetof the external electrodes located at an anterior of the patient; anddisplaying a posterior graphical depiction of the measured surrogatecardiac electrical activation times corresponding to a posterior subsetof the external electrodes located at a posterior of the patient. 37.The method of claim 31, wherein displaying the graphical depiction ofthe measured surrogate cardiac electrical activation times comprisesdisplaying a graphical depiction of the measured surrogate cardiacelectrical activation times about a graphical depiction of at least oneof an anterior side of a human torso and a posterior side of a humantorso.
 38. The method of claim 31, wherein displaying the graphicaldepiction of the measured surrogate cardiac electrical activation timescomprises displaying a graphical depiction of the measured surrogatecardiac electrical activation times about a graphical depiction of atleast one of an anterior side of a heart and a posterior side of aheart.
 39. The method of claim 31, wherein the computing apparatus isfurther configured to display, on the graphical user interface, at leastone electrocardiogram of the patient, wherein each of the at least oneelectrocardiogram are captured using at least one different electrode,and wherein the at least one electrocardiogram is time-aligned on thegraphical user interface.
 40. The method of claim 31, wherein theplurality of external surface electrodes are configured to be locatedproximate the skin of the torso of the patient.